Fluoroalkyl(meth)acrylate copolymers have been used in aqueous emulsions as in textile fabric treatment processes to provide coatings which impart desirable properties such as high levels of water-, alcohol-, and oil repellency to the fabrics. Aqueous emulsions of such fluoroalkyl (meth)acrylates copolymers, as disclosed in U.S. Pat. No. 5,344,903 are require an additional heat-cure step after application in order to impart the desired repellency traits to the fibers.
Fluorinated polymer compositions are used in the preparation of a wide variety of surface treatment materials to provide surface effects to substrates. Many such compositions are fluorinated acrylate polymers or copolymers which contain predominantly eight or more carbons in the perfluoroalkyl chain to provide the desired properties. Honda, et al., in Macromolecules, 2005, 38, 5699-5705 teach that for perfluoroalkyl chains of greater than 8 carbons, orientation of the perfluoroalkyl groups, designated Rf groups, is maintained in a parallel configuration while for such chains having 6 or less carbons, reorientation occurs. This reorientation is recited to decrease surface properties such as contact angle. Thus, polymers containing shorter perfluoroalkyl chains have traditionally not been commercially successful.
Alternatively, solvent-based polymer systems, particularly for alkyd coating and urethane coating compositions, do not require such a heat-cure step after application. However, alkyd and urethane coatings produced using solvent-based polymer systems have a tendency to be non-uniform and uneven after drying (air-cure), have low oil-contact angles, and poor cleanability ratings. Attempts have been made to overcome the problem of lack of evenness/uniformity, and to increase the cleanability and oil- and water-repellency of these types of coatings by the addition of a variety of surfactants and other compounds.
The present invention addresses the issues described above by introducing compositions comprised of solvent-based fluoroalkyl (meth)acrylate copolymers with short perfluoroalkyl groups of 6 or less carbons. They are utilized as coating additives and impart unexpectedly desirable surface effects such as: uniform spreading, increased water and oil contact angles, enhanced cleanability to the coated film and air-cured coated surface.